The function of NPLOC4 (NPL4 homolog, ubiquitin recognition factor, Ensembl gene identifier ENSG00000182446) is as follows. The ternary complex containing UFD1, VCP and NPLOC4 binds ubiquitinated proteins and is necessary for the export of misfolded proteins from the ER to the cytoplasm, where they are degraded by the proteasome. The NPLOC4-UFD1-VCP complex regulates spindle disassembly at the end of mitosis and is necessary for the formation of a closed nuclear envelope (By similarity). Acts as a negative regulator of type I interferon production via the complex formed with VCP and UFD1, which binds to RIGI and recruits RNF125 to promote ubiquitination and degradation of RIGI (PubMed:26471729). {ECO:0000250|UniProtKB:Q9ES54, ECO:0000269|PubMed:26471729}.